feat: add locally syncing and watchdog

internal/utility/hash.go

@@ -0,0 +1,41 @@
+package utility
+
+import (
+	"crypto/sha512"
+	"encoding/hex"
+	"io"
+	"mime/multipart"
+	"os"
+)
+
+func HashReader(r io.Reader) (string, error) {
+	h := sha512.New()
+	if _, err := io.Copy(h, r); err != nil {
+		return "", err
+	}
+
+	// return the sha checksum in hex
+	return hex.EncodeToString(h.Sum(nil)), nil
+	// alternatively return in base64
+	//return base64.StdEncoding.EncodeToString(h.Sum(nil)), nil
+}
+
+func HashUpload(fileHeader *multipart.FileHeader) (string, error) {
+	stream, err := fileHeader.Open()
+	if err != nil {
+		return "", err
+	}
+	defer stream.Close()
+
+	return HashReader(stream)
+}
+
+func HashFile(path string) (string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	return HashReader(file)
+}